Induction heating coil, energizing means therefor, and work-release means



March 25, 1947. H. A. STRICKLAND, JR 2,413,056

INDUCTION HEATING COIL, ENERGIZING MEANS THEREFOR AND WORK-RELEASE MEANSFiled Aug. 13, 1945 K III/11% E 5M1 WJW ATTORNEY Patented Mar. 25, 194.7

INDUCTION HEATING COIL, ENERGIZING MEANS THEREFOR, AND WORK-RELEASEMEANS Harold A. Strickland, Jr., Detroit, Mich., assignor, by mesneassignments, to The Budd Company, Philadelphia, Pa., a corporation ofPennsylvania Application August 13, 1943, Serial No. 498,459

6 Claims.

This invention relates to heating and timing apparatus for brazing, withparticular application to the brazing of gas-tight joints in ferrousmetal articles.

In certain manufacturing operations it is necessary to form a subsurfaceseal having gastight properties within the body of the article ofmanufacture. Such a process step is involved in the sealing of athreaded joint between the cap and the body of a shell designed fordetonation, the cap usually being threaded to the body of the shell atthe leading end thereof.

The objects of this invention may be summarized as follows: to provideheating means which may be readily applied to the interior of shells orthe like for the principal purpose of fusing metal in brazingoperations; to provide a heat treating apparatus for brazing which isautomatically self-timing; to provide automatic brazing apparatus forshells and the like in which after completion of the heating step theshell or other workpiece is automatically removed from proximity to theheating apparatus. Other objects related to structure and method willappear on consideration of the following description and of theaccompanying drawing in which:

Fig. 1 is a diagrammatic view of a shell positioned in heating cont-actwith the brazing apparatus.

Fig. 2 is a view similar to Fig. 1 but with the shell in dischargedposition.

Fig. 3 is a detail in section showing the method of supporting theshell; and

Fig. 4 i a sectional detail of a shell prior to the brazing operationand showing the solder ring in position; and

Fig. 5 is a view of the cross bar along lines 5-5 of Fig. 2.

By way of example, a shell I is illustrated in Fig. 1, the same having abody section II and a nose or cap section l2. As more clearly shown inFig. 4, the shell body section II is hollow and the forward end |3thereof is open and screwthreaded on its inner surface adjacent the endl3, there being a smooth annular inner recess l4 at the extreme limit ofthe end l3. The cap I2 is an elongated member having a central apertureI and a forward end roughly parabolic in general contour with a flatnose IS, the curvature I! of the outer tip portion conforming to thecurved outer surface H! of the adjoining section of the body end I3. Themid-section of the cap I2 is outwardly screw-threaded as at H) to engagethe similarly threaded section on the inner surface of the body at thefront end thereof. The threaded section IQ of the cap is radially insetfrom the adjacent outer periphery of the cap I2 and at the point ofofiset an annular groove or channel 20 is formed externally which isadapted to register with the channel l4 formed on the inner surface ofthe leading end |3 of the body to form a central cavity adapted toreceive a solder ring 2| of silver, silver alloy or any other suitablecomposition for brazing purposes.

A shell of the type described may of course be of any desired dimensionsbut frequently they are of such a size as to require some means ofsupport to facilitate movement into and from the heatingunit. Asillustrated, I have shown for this purpose a carriage consisting of abody 3| of wood, metal or other substance having a length adequate forthe support of the workpiece and mounted on wheels or rollers 32, a pairof the same being positioned at each end of the support 3|. Thelongitudinal upper surface of the body 3| is channeled in such manner asto give a contour similar to that of the workpiece, the channel 33 beingindicated. The rollers 32 are preferably shaped with flanges 34 so as tobe retained on rails 35 as indicated in Fig. 3. With this means ofsupport the workpiece may readily be moved along the track into or outof engagement with the heating unit. The rails 35 are mounted on a base36 which may, as shown in Figs. 1 and 2, terminate at one end in anupstanding standard or block 31 adapted to receive the switch operatingmechanism as will now be described.

The switch operating mechanism 49 includes a rod 4| slidably mountedupon the pillar 31. This rod is provided at either end with operatingmeans for bringing about the energization or deenergization of theheating unit. At the forward end of the rod a collar 42 is placed beyondwhich extends a contact pin 43, the latter being adapted to make slidingcontact with flexible switch elements 44. On the rear end of rod 4|there is secured a stop and a contact plate 46. The stop 45 is adaptedto engage the end of a coil spring 41 enclosed within the standard 31 ina cavity surrounding the control rod 4|; the other end of the springengages the forward end of the cavity that normally the spring is undercompression tending to force the control rod rearwardly to disengage thecontact pin 43 from the slidable contact members 44 and simultaneouslymove the contact plate 46 rearwardly against the annular nose l6 of ashell l0 mounted on the carriage 30, thus tending to move the shellrearwardly on the track 35.

The electrical energization of the shell nose is accomplished by aninductor coil 50, the conductor being tubular and substantially squarein cross section, and the coil being wound to conform to the generalcurvature of the cap of the shell so that when the shell is positionedwith its nose against the contact plate 46 and the spring 47 undercompression the approximate axial center of the coil is in transversealignment with the ring 2 I. By this means the induced heat is spreaduniformly through the shell nose with reference to the ring thusaccomplishing the efficient heating thereof and insuring an equable heatdistribution to the silver ring 2!.

The ends of coil 50 are connected through the double pole contactor 5!to a source of high 'requency current 52, power factor correction beingsecured by capacitor Bil. Also power is received from an appropriatesource 53 for the operation of the control mechanism. The controlmechanism includes the sliding spring switch previously mentioned andcircuit connections, including the contactor operating coil 54, forbringing about closure and opening of the main power circuit of the'coil50' upon closure and openingof switch 44=by means of the sliding contactpin 43.

As appears from the preceding description the operation of apparatusinvolves the mounting of the shell uponthe carriage 3D, the movement ofthe shell into operative relationship with the inductor 59, thesimultaneous closure of slide switch 44 by the slide pin 4| moved underpressureof th cross bar 46-by the nose of the-shell, the closure of themain power circuit by the control contactor 5|, the energizationof coil50 and the consequent heating of the brazing ring 2| to the fusiontemperature, and finally theautomatic movement of the shell fromoperative position accompanied by opening of control switch and theassociated opening of the main power circuit in the control contastor5|.

An outstanding feature involved in the structural. and circuitalarrangements described is that controlling the automatic movement of theshell from operative position in the inductor unit asshown in Fig. 1 tothe inoperative position of Fig. 2. This automatic movement iscontrolled by at least twoagencies and possibly three, first agent isthespring 41 which normally tends to force the shell away from operativeposition. However, this tendency is ordinarily restrained through themagnetic action of the inductor in relation to the ferromagneti:material of the shell cap, this action being such as to hold the,

shell closely in contact with the cross bar 46 and in operative positionwithin the inductor. However, as the temperature of the cap andassociated shell section increases the intensity of the magnetic actiontends to diminish until, at the recalescence temperature all retractivemagnetic action ceases between the shell cap and coil; hence at thispoint the spring 4'! is free to exert its pressure on the shell nose andforce the shell rearwardly on the track 35 to the position of Fig. 2.There is associated with this rearward shell movement a limited amountof motor action, the component of electro-magnetic forces resulting fromthe rapidly alternating flux of the coil in a non-magnetic coilconductor tending to force the conductor, that is shell and cap, out

The.

of the high density section of electro-magnetic flux.

= present the inventive features clearly.

Thus it appears that by the arrangement of 1 there is provided effectivemeans for fusion of an embedded ring in a metallic joint of a movableunit and subsequently, by the means of ching a temperature suificientfor fusion, seedling a separation of the unit from the heating means andthe opening of the heat circuit.

It is apparent that the description of the invention as set forth isdiagrammati: in order to Obviously, modification of the invention may bemade involving structural changes in the mode of supporting the sheii,the precise configuration of the heating coil, the type of spring orgravity structure utilized for moving the contact pin 4| and other ofthe cooperating elements and therefore no limitation is. intended by thestructural elements as disclosed, other than may be included within thescope of the claims hereto appended.

What is claimed is:

1. In a brazing apparatus, an inductive heating coil positioned with itsaxis approximately horizontal, means for supporting a ferro-magneticworkpiece for reciprocating movement into and out of heating positionwithin said coll, work-release means adapted to engage said workpiecewhen in position to be heated and tending to force said workpiece out ofheating position, and power means for energization of said heating coilwhereby said workpiece is held in release means adapted to engage saidworkpiecewhen in position to be heated and tending to force saidworkpieceout of heating position, and power meansfor energization ofsaidheating coil whereby said workpiece is held in heating positionagainst the force of said release means and heat is supplied thereto andmeans connected to, and operated-by, said work-release means, for

energization of said power means.

3. In brazing apparatus, an inductive heating coil positioned with itsaxis approximately horizontal, means for supporting a ferromagneticworkpiece for reciprocating movement into'and out of heating positionwithin said coil, workrelease means adapted-to engage said workpiecewhen in position to be heated and tending to force said workpiece-out ofheating position, and power means for energization of said heating coilwhereby said workpiece is held in heating position against the force ofsaid work-release means and heat is supplied thereto, said work-releasemeans being effective to release the workpiece only on heating of theworkpiece to the temperature of recalescence.

4. In brazing apparatus for ferromagnetic ma a circuit for energizationof said heating coil, said circuit including power-controlled switchmechanism, and circuit means for energization of said power-controlledmechanism, said means including a spring-operated push-out rod, acontact plate on one end of said rod adapted to engage the workpiecewhen in heat treating position against the force of said spring andswitch means on the other end of said rod adapted, when the rod is movedto heat treating position, to energize said circuit means, said rodforcing said workpiece away from the heating coil after demagnetizationof the workpiece.

6. In apparatus for brazing a ferro-magnetic workpiece, a heating coil,circuit connections to said coil whereby energy for heating and holdingthe workpiece in operative position within the coil are supplied,push-out means positioned adjacent one end of said coil, operative toremove the workpiece automatically from heating position when thetemperature thereof approximates that of recalescence, comprising areciprocable rod movable to inner and outer positions, and spring meansfor urging the rod in a direction toward the workpiece to the innerposition thereof, and switch means operated by the rod of said push-outmeans when in outer position for closing said circuit connections, saidpush-out rod being forced to outer position by insertion of theworkpiece.

HAROLD A. STRICKLAND, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Denhard June 30, 1914 Somes Mar. 24,1942 Number

